1. Field of the Invention
This invention relates to the field of silver halide elements and more particularly to silver halide elements with improved speed and low fog. Still more particularly, this invention relates to a novel group of silver halide sensitizers useful in said elements.
2. Discussion of the Prior Art
Silver halide elements useful in recording photographic images are well-known in the prior art and this entire art field has been well-described. In an effort to increase the usefulness of these elements, there have been numerous attempts to increase the speed of the film elements made from these silver halide elements. Many of these attempts have been made by adding various adjuvants to the silver halide during the emulsion making step. These additives are usually sulfur compounds as it is well-known that the addition of compounds that contain labile sulfur will indeed act as a speed increasing adjuvant. However, most of these adjuvants also cause an undesirable increase in emulsion fog. So, the user must take care that not too much of the speed increasing compound is added.
Various cysteine compounds have been tried in silver halide emulsions to get the increased speed effect. Although some of these have been successful, fog is also a problem with these compounds.